The present invention relates to an improved die set usable in a compression tool, and relates more particularly to a dimpling die set for use on a flange or the like of a workpiece wherein each dimpling die has an array of projections which deform the surface of the workpiece upon compression by the tool.
This invention relates to a die set to be used for the installation of a compression rail connector to railroad rails for grounding wires, or wires which are used for signalling, communication, or power applications. In the installation of such compression connectors, it is necessary to create a dimpled surface on a rail upon which surface, the connector will be placed. The dimpled surface with the compression connector acts to create greater surface area on the underlying contact area of the workpiece so as to insure better conductivity and redundancy in the connection.
In addition, the formation of a dimpling pattern on the surface of a workpiece creates an enhanced mechanical connection between the compression connector and the surface which is contacted. This mechanical interface between correspondingly formed surfaces of the die and the connector has many advantages. Specifically, when a compression rail connector is crimped onto the rail foot over the preformed dimples, the material of the connector flows into the dimples and effectively interlocks the connector with the rail foot thus providing a strong attachment of a connector to the rail. Thus, the dimpling of one or more surfaces of a rail is desirable for enhanced electrical connection between the connector and the rail as well as for providing a mechanical connection therebetween.
In order to create dimpling surfaces on a railroad rail, it is necessary to provide a tool which is made of a material that is harder than the workpiece surface onto which a dimple is to be made. In addition, the tool must have projections which likewise are capable of causing the dimpling, and so must have a geometry which is capable of deforming the surface of the member, e.g. the rail, as well as providing a geometry sufficiently corresponding to the geometry of the connector which will be seated onto the then formed dimpled surface. In addition, in the circumstance where the surface to be dimpled is disposed at an angle other than 0.degree. to the horizontal, it is often necessary to orient the surface which contains the deforming dimpling projections at an angle which is congruent with the angle of the surface to be dimpled. For example, the base flange of a railroad rail has a top surface which is angled approximately 14.degree. with the horizontal. If the projections on the upper die which engage with the upper surface were not disposed at such an angle relative to this surface, then there would be created only a partial dimpled area, which would be ineffectual for the purposes of a successful long lasting electrical and mechanical connection.
Accordingly, it is an object of the present invention to provide a dimpling die set wherein the projections which are responsible for causing deformation in a surface to be dimpled are arranged at an angle corresponding to the angle of the surface to which the die is to be impacted.
Also, with such dimpling die sets, it is important to be able to set the die at a location on a surface, for example a given distance from a side edge, so that the placement of the dimpled surface is uniform and constant.
It is still a further object of the invention to provide a dimpling die set of the aforementioned type wherein the die has a locating portion which locates the die at a given distance from one side edge of the surface to be deformed so as to produce repeatable, uniformly located dimpled areas on the surface to be worked.
Still a further object of the invention is to provide a die of the aforementioned type which is capable of being used in standard compression tools.
Other objects and advantages of the invention will become apparent from the following disclosure and the appended claims.